What is the key mechanical difference between optical image stabilization and sensor-shift stabilization inside the iPhone, and how does each improve a photo's sharpness?

Optical Image Stabilization, or OIS, inside the iPhone works by mechanically shifting specific lens elements within the camera module. When the iPhone experiences shake, internal gyroscopes and accelerometers detect the camera's movement. Tiny electromagnetic actuators then precisely move one or more lens elements in the direction opposite to the detected shake. This movement redirects the incoming light path, effectively keeping the image projected onto the camera's sensor stationary, even as the phone itself moves. This action prevents motion blur, which is the undesirable smearing of an image that....